Isopropyl-(3-oxopentenyl)-cyclopentenes

ABSTRACT

Novel cyclopentene derivatives, a process for making same and odorant compositions containing the novel compounds are disclosed.

FIELD OF THE INVENTION

This invention relates to the fields of new chemicals and odorant compositions.

SUMMARY OF THE INVENTION

The cyclopentene derivatives provided by this invention have the following general formula ##SPC1##

Wherein R¹ and R² each independently represent a hydrogen atom or a lower alkyl group and the broken line denotes an optional bond.

The term "lower alkyl" is used in this description and in the accompanying claims to mean a straight-chain or branched-chain group containing 1-6 carbon atoms (e.g. methyl, ethyl, propyl, isopropyl or tert.butyl). A preferred lower alkyl group is the methyl group.

According to the process provided by this invention, the cyclopentene derivatives of formula I are manufactured by oxidising a compound of the general formula ##SPC2##

Wherein R¹, R² and the broken line have the significance given earlier.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The oxidation can be carried out in a manner known per se according to methods which are generally known for the oxidation of allylic hydroxy groups. Examples of oxidising agents which can be used are chromic acid (in its various forms such as, for example, Jones reagent), activated manganese dioxide, SO₃ (preferably as the pyridine complex in the presence of dimethyl sulphoxide and triethylamine), silver oxide or silver carbonate in the presence of diatomaceous earth. The working up of the oxidation mixture as well as the purification of the cyclopentene derivatives of formula I can be carried out according to customary methods.

The starting materials of formula II can be prepared in a manner known per se from a compound of the general formula ##SPC3##

Wherein R¹ and the broken line have the significance given earlier, by reaction with an organometallic compound, especially with an alkali metal acetylide or with a Grignard compound of the general formula ##SPC4##

Wherein R² has the significance given earlier and Hal represents a chlorine or bromine atom.

When a compound of formula III is reacted with an acetylide it is necessary to catalytically partially hydrogenate the initially obtained compound of the general formula ##SPC5##

Wherein R¹ and the broken line have the significance given earlier, in a manner known per se; for example, in the presence of a Lindlar catalyst (Pd/CaCO₃ deactivated with PbO).

Insofar as they are not known, the compounds of formula III can be prepared, for example, by reacting 3-isopropenyl-1-methyl-2-methylene-cyclopentan-1-ol with a vinylether of the general formula ##SPC6##

Wherein R¹ has the significance given earlier and R represents an alkyl group, and, if desired, hydrogenating a resulting 3-isopropenyl-cyclopentene of the general formula ##SPC7##

Wherein R¹ has the significance given earlier, to give the corresponding 3-isopropyl compound.

The cyclopentene derivatives of formula I possess particular fragrance properties, especially in the foreground is a woody basic note. They can accordingly be used as odorants in perfumery; for example, in the manufacture or for the modification of the fragrance of odorant compositions such as perfumes, perfume bases, etc by addition of olfactory perceptible amounts (e.g. 0.1-10 wt %) to mixtures of known odorants. The cyclopentene derivatives of formula I can be used alone or in the form of odorant compositions for the perfuming of technical and cosmetic products of all types; for example, of solid and liquid detergents, synthetic washing agents, aerosols, soaps, creams, lotions, etc in concentrations of, for example, about 0.001-0.1 wt %. They can also be used as starting materials for the manufacture of other odorants.

The following Examples illustrate the process provided by the present invention:

EXAMPLE 1

A solution of 2.1 g of 2-(3-hydroxy-4-pentenyl)-3-isopropyl-1-methyl-1-cyclopentene in 100 ml of acetone was treated at -10°C with 4 ml of Jones reagent. After 2 minutes, the solution was poured into an ice-cold 2-N soda solution and the mixture extracted with ether. The extract was worked up in the usual manner and yielded 2 g of a yellowish oil which, after distillation under reduced pressure, gave 1.6 g of pure 3-isopropyl-1-methyl-2-(3-oxo-4-pentenyl)-1-cyclopentene; b.p. ₀.01 = 65°C;

IR (film): ν = 1700/1685, 1620, 1470, 1402, 1385, 1365, 1185, 1100, 990, 965 cm⁻ ¹. Odor: woody, ketone-like.

EXAMPLE 2

In a manner analogous to that described in Example 1, from 2-(3-hydroxy-4-methyl-4-pentenyl)-3-isopropyl-1-methyl-1-cyclopentene there was prepared 3-isopropyl-1-methyl-2-(4-methyl-3-oxo-4-pentenyl)-1-cyclopentene; b.p. ₀.01 = 80°C;

UV (cyclohexane): Λ_(max) = 214 nm (ε = 9000); IR (film): ν = 1680, 1635, 1465/55, 1385, 1365, 1090, 935 cm⁻ ¹. Odor: woody, ionone-like, sweet, fig-like, somewhat fruity.

EXAMPLE 3

In a manner analogous to that described in Example 1, from 2-(3-hydroxy-2-methyl-4-pentenyl)-3-isopropyl-1-methyl-1-cyclopentene there was prepared 3-isopropyl-1-methyl-2-(2-methyl-3-oxo-4-pentenyl)-1-cyclopentene; b.p. ₀.005 = 78°C;

UV (cyclohexane): Λ_(max) = 212 nm (κ = 8400); IR (film): ν = 1700, 1680, 1615, 1460, 1400, 1385, 1365, 1030, 985/975 cm⁻ ¹. Odor: fresh, woody, spicy.

EXAMPLE 4

In a manner analogous to that described in Example 1, from 2-(3-hydroxy-2,4-dimethyl-4-pentenyl)-3-isopropyl-1-methyl-1-cyclopentene there was prepared 3-isopropyl-1-methyl-2-(2,4-dimethyl-3-oxo-4-pentenyl)-1-cyclopentene; b.p. ₀.01 = 90°C;

UV (cyclohexane): Λ_(max) = 212 nm (ε = 7900); IR (film): ν = 1680, 1630, 1460, 1380, 1370, 930 cm⁻ ¹. Odor: woody, cedar-like, fresh.

EXAMPLE 5

A solution of 20 g of 2-(3-hydroxy-4-pentenyl)-3-isopropenyl-1-methyl-1-cyclopentene in 1000 ml of acetone was mixed with 40 ml of Jones reagent with stirring at -10°C within 20 minutes. The mixture was stirred for a further 5 minutes at -5°C, poured into an excess of ice-cold 2-N soda solution and extracted with ether. The extract was worked up in the usual manner and yielded 18.5 g of a bright yellow oil which, after distillation under reduced pressure, gave 16 g of pure 3-isopropenyl-1-methyl-2-(3-oxo-4-pentenyl)-1-cyclopentene; b.p. ₀.001 48°C;

IR (film): ν = 3100, 1700/1685, 1645, 1620, 1442, 1402, 1375, 1100, 990, 968, 895 cm⁻ ¹. Odor: pleasant floral-ester-like, geranium-like, linalool-like.

EXAMPLE 6

In a manner analogous to that described in Example 5, from 2-(3-hydroxy-2-methyl-4-pentenyl)-3-isopropenyl-1-methyl-1-cyclopentene there was prepared 3-isopropenyl-1-methyl-2-(2-methyl-3-oxo-4-pentenyl)-1-cyclopentene; b.p. ₀.02 = 84°C;

UV (cyclohexane): Λ_(max) = 213 nm (ε = 9500); IR (film): ν = 3100, 1702, 1682, 1645, 1615, 1455/40, 1405, 1375, 1030, 990, 975, 892 cm⁻ ¹. Odor: fatty, similar to undecylenic acid.

EXAMPLE 7

In a manner analogous to that described in Example 5, from 2-(3-hydroxy-4-methyl-4-pentenyl)-3-isopropenyl-1-methyl-1-cyclopentene there was prepared 3-isopropenyl-1-methyl-2-(4-methyl-3-oxo-4-pentenyl)-1-cyclopentene; b.p. ₀.01 = 88°C;

UV (cyclohexane); Λ_(max) = 213 nm (ε = 9900); IR (film): ν = 3110, 1680, 1645, 1450, 1375, 1090, 935, 895 cm⁻ ¹. Odor: fresh, woody, cedar-like, green.

EXAMPLE 8

In a manner analogous to that described in Example 5, from 2-(3-hydroxy-2,4-dimethyl-4-pentenyl)-3-isopropenyl-1-methyl-1-cyclopentene there was prepared 3-isopropenyl-1-methyl-2-(2,4-dimethyl-3-oxo-4-pentenyl)-1-cyclopentene; b.p. ₀.01 = 92°C;

UV (cyclohexane): Λ_(max) = 216 nm (ε = 8800) IR (film): ν = 3110, 1680, 1645, 1455, 1375, 935, 895 cm⁻ ¹. Odor: woody, cedar-like, camphoraceous.

The following Examples illustrate odorant compositions containing the cyclopentene derivatives provided by the invention.

EXAMPLE A Odorant composition containing 3-isopropenyl-1-methyl-2-(3-oxo-4-pentenyl)-1-cyclopentene.

    ______________________________________                                                                Parts by weight                                         ______________________________________                                         Phenylethyl alcohol      400                                                   Linalool                 30                                                    Geranyl acetate          20                                                    Eugenol                  10                                                    Nonylaldehyde ( 1% in phthalic                                                   acid diethyl ester)    10                                                    Nerol                    50                                                    Citral                   5                                                     6-Methylionone           15                                                    Rhodionol 70 Givaudan (Rhodinol/Citronellol                                                             80                                                      in ratio of 70/30)                                                           Citronellol              180                                                   Baccartol Givaudan (condensation product                                         of citronella oilacetone)                                                                             100                                                   3-Isopropenyl-1-methyl-2-(3-oxo-                                                 4-pentenyl)-1-cyclopentene                                                                            100                                                                            1000                                                  ______________________________________                                    

By the addition of 3-isopropenyl-1-methyl-2-(3-oxo-4-pentenyl)-1-cyclopentene, the rose-like note of the composition is intensified.

EXAMPLE B Odorant composition containing 3-isopropyl-1-methyl-2-(4-methyl-3-oxo-4-pentenyl)-1-cyclopentene.

    ______________________________________                                                                Parts by weight                                         ______________________________________                                         Bergamot oil             200                                                   Oak moss soluble         60                                                    Vetiveryl acetate        40                                                    Eugenol                  40                                                    Lavandin                 80                                                    Lavender oil             100                                                   Sandalwood oil           100                                                   Cedryl acetate           120                                                   Musk ambrette            100                                                   Lemon oil Italian        40                                                    Sauge sclaree 20                                                               Orange oil Californian   20                                                    Thyme oil white          20                                                    3-Isopropyl-1-methyl-2-(4-methyl-                                                3-oxo-4-pentenyl)-1-cyclopentene                                                                      60                                                                             1000                                                  ______________________________________                                    

By the addition of 3-isopropyl-1-methyl-2-(4-methyl-3-oxo-4-pentenyl)-1-cyclopentene, the fresh, lavender-like note of the composition is emphasised. 

What we claim is:
 1. Cyclopentene derivatives of the general formula ##SPC8##wherein R¹ and R² each independently represent a hydrogen atom or a lower alkyl group.
 2. 3-Isopropyl-1-methyl-2-(3-oxo-4-pentenyl)-1-cyclopentene.
 3. 3-Isopropyl-1-methyl-2-(4-methyl-3-oxo-4-pentenyl)-1-cyclopentene.
 4. 3-Isopropyl-1-methyl-2-(2-methyl-3-oxo-4-pentenyl)-1-cyclopentene.
 5. 3-Isopropyl-1-methyl-2-(2,4-dimethyl-3-oxo-4-pentenyl)-1-cyclopentene. 